Non-volatile plasticizers and flow aids for polyesters

ABSTRACT

The use of a specified molecular weight range of poly(alkylene ether)s, such as poly(ethylene glycol) (PEG), poly(tetramethylene glycol) (PTMG), and poly(propylene glycol) (PPG), and end-capped poly(alkylene ether)s, as plasticizers for polyesters such as poly(ethylene terephthalate) (PET), poly(propylene terephthalate) (PPT), poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) (PEN), and poly(1,4-cyclohexanedimethylene terephthalate) (PCT), that are non-volatile during drying processes as well as during melt processing. Such poly(alkylene ether)s and end-capped poly(alkylene ether)s decrease the melt viscosity of the polymer matrix and depress the glass transition temperature, and thereby improve the processability of polyesters.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional application No.60/082,724, filed Apr. 23, 1998.

FIELD OF THE INVENTION

This invention concerns non-volatile blends of one or more poly(alkyleneether)s or end-capped poly(alkylene ether)s with polyesters that providefaster crystallization rates at lower mold temperatures than polyestersalone.

BACKGROUND OF THE INVENTION

Crystallization rate as a function of temperature is often critical wheninjection molding semicrystalline engineering thermoplastics.Crystallization rate as a function of temperature controls the optimummold temperature and cycle time of the process. It is desirable tooperate at mold temperatures less than 110° C. because this allows forthe use of traditional water heated, as opposed to oil heated, molds.These low mold temperatures also allow the process to operate at anoptimum crystallization rate, which in turn translates into shortercycle times and improved economies.

The use of a plasticizer is well known to the art to enhancecrystallization rate. A plasticizer typically decreases the meltviscosity and depresses the glass transition temperature of thethermoplastic, which in turn increases crystallization rate at a lowertemperature. Common plasticizers for polyester engineering plastics arelow molecular weight organic esters such as neopentylglycoldibenzoate(Benzoflex S312) and dipropyleneglycoldienzoate (Benzoflex 9-88).Alternate plasticizers are poly(ether esters) such as copolyesters ofpoly(butylene terephthalate) and poly(tetramethylene glycol) (Hytrel).

Another key requirement when processing polyesters is drying. It isimportant to minimize or eliminate moisture from a polyester prior tomelt processing, otherwise hydrolytic degradation occurs resulting in adiminished molecular weight and unacceptable mechanical properties.Furthermore, because drying results in an increased processing cost itis important to minimize the drying time required. Thus it is anadvantage to dry at higher temperatures as this reduces the timenecessary. However, many of the plasticizers and flow aids used in theart are volatile under drying conditions. Volatile emissions areundesirable because they contaminate the dryers and increase cleaningand maintenance costs.

Low molecular weight organic esters are known plasticizers forpolyesters, but they tend to be volatile in the dryers, which can beremedied only by lowering drying temperatures and increasing dryingtime. Increasing the molecular weight of organic esters is known toreduce volatility during drying, however it is taught that this approachis not effective because the higher molecular organic esters are nolonger plasticizers.

Low volatility has previously been considered advantageous because itallows higher temperatures and shorter times for melt processing.Poly(alkylene ether)s have been reported to be such non-volatileprocessing aids for polyesters. Suprisingly, however, many of thesenon-volatile poly(alkylene ether)s are volatile during the dryingprocess over the relatively long times required for drying. Thisvolatility results in contaminated dryers and loss of productivity.

SUMMARY OF THE INVENTION

This invention pertains to the use of a specified molecular weight rangeof poly(alkylene ether)s, such as poly(ethylene glycol) (PEG),poly(tetramethylene glycol) (PTMG), and poly(propylene glycol) (PPG),and end-capped poly(alkylene ether)s, as plasticizers for polyesterssuch as poly(ethylene terephthalate) (PET), poly(propyleneterephthalate) (PPT), poly(butylene terephthalate) (PEBT), poly(ethylenenaphthalate) (PEN), and poly(1,4-cyclohexanedimethylene terephthalate)(PCT), that are non-volatile during drying processes as well as duringmelt processing. Such poly(alkylene ether)s and end-capped poly(alkyleneether)s decrease the melt viscosity of the polymer matrix and depressthe glass transition temperature, and thereby improve the processabilityof polyesters.

Thus, in accordance with the purpose(s) of this invention, as embodiedand broadly described herein, this invention, in one aspect, relates toa blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I):

wherein:

i. m is an integer of from 1 to 3;

ii. n is an integer of from 5 to 140;

iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbonsor less;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedinethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 200° C.

In another embodiment the invention provides a blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is 1;

ii. n is an integer of from 10 to 25;

iii. X is selected from hydrogen, methyl, ethyl, and propyl;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the number average molecular weight of A and B summed is greater thanabout 250; and

vi. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 240° C.

In another embodiment the invention provides a process for making acomposition comprising melt mixing a blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is an integer of from 1 to 3;

ii. n is an integer of from 5 to 140;

iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbonsor less;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephithalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 200° C.;

wherein the melt mixing is performed under sufficiently mild conditionsto avoid reaction between the polyester and the poly(alkylene ether).

In still another embodiment the invention provides a process for makinga composition comprising melt mixing a blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is 1;

ii. n is an integer of from 10 to 25;

iii. X is selected from hydrogen, methyl, ethyl, and propyl;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the number average molecular weight of A and B summed is greater thanabout 250; and

vi. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terepthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 240° C.

wherein the melt mixing is performed under sufficiently mild conditionsto avoid reaction between the polyester and the poly(alkylene ether)

In still another embodiment the invention provides a method of usingpolyester blends to reduce volatile emissions during drying, comprisingproviding a polyester blend of this invention, and drying the polyesterblend at greater than 100° C. In a still further embodiment theinvention provides a method of using polyester blends to reduce volatileemissions during molding, comprising providing a polyester blend of thisinvention, and molding the polyester blend into a useful article.

Additional advantages of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

DISCUSSION

The present invention may be understood more readily by reference to thefollowing detailed description of preferred embodiments of the inventionand the Examples included therein.

Before the present compounds, compositions and methods are disclosed anddescribed, it is to be understood that this invention is not limited tospecific methods or compositions, as such may, of course, vary. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting.

Use of Terms

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a polyester” includes mixtures of polyesters, reference to“a poly(alkylene ether)” includes mixtures of two or more suchpoly(alkylene ether)s, and the like.

Ranges are often expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Still another embodiment includesfrom the one particular value and/or to the other particular value, butnot including the particular value(s). Similarly, when values areexpressed as approximations, by use of the antecedent “about”, it willbe understood that the particular value forms another embodiment.

Definitions

In this specification and in the claims which follow, reference will bemade to a number of terms which shall be defined to have the followingmeanings:

References in the specification and concluding claims to parts byweight, of a particular element or component in a composition orarticle, denotes the weight relationship between the element orcomponent and any other elements or components in the composition orarticle for which a part by weight is expressed. Thus, in a compoundcontaining 2 parts by weight of component X and 5 parts by weightcomponent Y, X and Y are present at a weight ratio of 2:5, and arepresent in such ratio regardless of whether additional components arecontained in the compound.

A residue of a chemical species, as used in the specification andconcluding claims, refers to the moiety that is the resulting product ofthe chemical species in a particular reaction scheme or subsequentformulation or chemical product, regardless of whether the moiety isactually obtained from the chemical species. Thus, an ethylene glycolresidue in a polyester refers to one or more —OCH₂CH₂O— units in thepolyester, regardless of whether ethylene glycol was used to prepare thepolyester. Similarly, a sebacic acid residue in a polyester refers toone or more —CO(CH₂)₈CO— moieties in the polyester, regardless ofwhether the residue is obtained by reacting sebacic acid or an esterthereof to obtain the polyester.

The term “alkyl” as used herein refers to a branched or unbranched,aliphatic or cyclic, saturated hydrocarbon group of 1 to 24 carbonatoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl andthe like. Preferred alkyl groups herein contain from 1 to 12 carbonatoms. The term “lower alkyl” intends an alkyl group of from one to sixcarbon atoms, preferably from one to four carbon atoms. The term“cycloalkyl,” intends a cyclic alkyl group of from three to eight,preferably five or six carbon atoms.

The term “acyl” means any group having the formula RC═O, wherein R isaryl or alkyl. Examples include acetyl, propanoyl, and benzoyl.

The term “aryl” means any unsaturated cyclic group of from three to sixcarbon atoms or heteroatoms. Examples include benzyl and pyridinyl.

“PPHR” means parts per 100 parts resin, and is used to express therelative parts by weight of an ingredient in a resinous blend orcomposition. Thus, in a composition that contains 5 pphr of ingredientA, there is present 5 weight parts ingredient A, and 100 weight parts ofresin.

“Fatty acid” means a long chain carboxylic acid, and can typically berepresented by the formula CH₃(CH₂)_(n)C(O)OH, wherein n is from about 8to about 20. Preferred fatty acids are unsaturated, and include lauricacid, myristic acid, palmitic acid, and stearic acid, with lauric acidbeing most preferred.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances where itdoes not. For example, the phrase “optionally substituted lower alkyl”means that the lower alkyl group may or may not be substituted and thatthe description includes both unsubstituted lower alkyl and lower alkylwhere there is substitution.

By the term “effective amount” of a compound or property as providedherein is meant such amount as is capable of performing the function ofthe compound or property for which an effective amount is expressed. Aswill be pointed out below, the exact amount required will vary fromprocess to process, depending on recognized variables such as thecompounds employed and the processing conditions observed. Thus, it isnot possible to specify an exact “effective amount.” However, anappropriate effective amount may be determined by one of ordinary skillin the art using only routine experimentation.

The term “modified” is often used herein to describe polymers and meansthat a particular monomeric unit that would typically make up the purepolymer has been replaced by another monomeric unit that shares a commonpolymerization capacity with the replaced monomeric unit. Thus, forexample, it is possible to substitute diol residues for glycol inpoly(ethylene glycol), in which case the poly(ethylene glycol) will be“modified” with the diol. If the poly(ethylene glycol) is modified witha mole percentage of the diol, then such a mole percentage is based uponthe total number of moles of glycol that would be present in the purepolymer but for the modification. Thus, in a poly(ethylene glycol) thathas been modified by 50 mole % with a diol, the diol and glycol residuesare present in equimolar amounts.

The term “polyester” includes copolyesters.

In accordance with the purpose(s) of this invention, as embodied andbroadly described herein, this invention, in one aspect, relates to ablend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I):

wherein:

i. m is an integer of from 1 to 3, preferably 1;

ii. n is an integer of from 5 to 140, preferably 5 to 10 to 25;

iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbonsor less, preferably hydrogen, methyl, ethyl, or propyl, most preferablyhydrogen;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons, and are preferably independently theresidue of one or more fatty acids having from about 10 to about 20carbons;

v. optionally, the number average molecular weight of A and B summed ispreferably greater than about 250, even more preferably greater thanabout 350; and

vi. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000, preferably from about 900 to about 2500,and more preferably from about 900 to about 1600; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 200° C., preferablygreater than 240° C., and even more preferably greater than 260° C.

Several ranges and values are given for some of the variables recitedabove, and it will be understood that the invention encompasses allcombinations of the variables. Thus, in another embodiment the inventionprovides a blend comprising:

a. from about i to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is 1;

ii. n is an integer of from 10 to 25;

iii. X is selected from hydrogen, methyl, ethyl, and propyl, preferablyhydrogen;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons, and are preferably independently fattyacid residues comprising having from about 10 to about 20 carbons;

v. the number average molecular weight of A and B summed is greater thanabout 250; and

vi. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000, preferably from about 900 to about 2500,and even more preferably from about 900 to about 1600; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 240° C.

In a particularly preferred embodiment the polyester is poly(ethyleneterephthalate) having a melting temperature greater than about 240° C.In another particularly preferred embodiment the polyester ispoly(1,4-cyclohexanedimethylene terephthalate) having a meltingtemperature greater than about 260° C.

In still another embodiment the blend comprises a phosphorous compound,such as a phosphite, phosphate, or phosphonate. These phosphorouscontaining compounds deactivate any catalyst remaining in the blend, toinhibit or prevent further reaction of the polyester and/orpoly(alkylene ether) during processing of the blend. In a particularlypreferred embodiment the blend comprises a phosphorous compound, and thepolyester is poly(1,4-cyclohexanedimethylene terephthalate) having amelting temperature greater than about 260° C.

In one particular blend:

a. X is hydrogen;

b. A and B are independently the residue of one or more fatty acidshaving from about 10 to about 20 carbons;

c. the poly(alkylene ether) has a number average molecular weight offrom about 900 to about 1600;

d. the polyester is poly(1,4-cyclohexanedimethylene terephthalate)having a melting temperature greater than about 260° C.;

e. the blend further comprises a phosphorous compound; and

f. the blend further comprises from about 30 to about 100 pphr of glassfiber.

The poly(alkylene ether)s and end-capped poly(alkylene ether)s of thepresent invention decrease the melt viscosity of the polymer matrix anddepress the glass transition temperature, thereby improving theprocessability of polyesters.

The poly(alkylene ether)s or end-capped poly(alkylene ether)s arepreferably limited by molecular weight. Poly(alkylene ether)s withmolecular weights below the recited ranges tend to be volatile duringdrying whereas poly(alkylene ether)s with a molecular weight above therecited ranges tend to phase separate from the polyester and beineffective plasticizers.

It was unexpected that poly(alkylene ether)s in this molecular weightrange would be effective plasticizers because the prior art stresses theimportance of low molecular weight organic compounds, desired carbonatom to ester bond ratios, branching, or aromatic functionality toprovide compatibility with the matrix resin. The prior art teaches thatwithout this compatibility the additives are ineffective processingaids. Furthermore, although the prior art teaches the importance of lowmolecular weight, it has been suprisingly discovered that highermolecular weights are not only acceptable, but desired. Higher molecularweight poly(alkylene ether)s and end-capped poly(alkylene ether)s(within the preferred range), remain compatible with the distinctadvantage of being less volatile during drying.

Preferred poly(alkylene ether)s include poly(ethylene glycol),poly(tetramethylene glycol), poly(propylene glycol), and mixturesthereof. These poly(alkylene glycol)s can either be end-capped or not.In one embodiment the poly(alkylene ether) is end-capped by reacting theterminal hydroxyl groups with epoxy, ether, or carboxylic acidcompounds. For example if the poly(alkylene ether) is endcapped with acarboxylic acid compound (preferably a fatty acid) then an organic esterfunctionality would be obtained. End-capped poly(alkylene ether)s, suchas the organic esters of poly(alkylene ether)s, are preferred becausethey improve the thermal stability of the poly(alkylene ether). However,the organic ester is not critical to compatibility or plasticization ofthe polyester.

Endcapping serves the beneficial role of reducing the likelihood ofreaction between the polyester and poly(alkylene ether). This role isimportant to preserve the semicrystalline character of the polyesterblend. Thus, the poly(alkylene ether) is preferably endcapped on atleast one end, and more preferably on both. Other ways to reduce thelikelihood of reaction include addition of a catalyst deactivating agent(such as a phosphorous compound), and processing the blend under mildconditions.

Other additives, such as glass fiber, carbon fiber, reinforcing agents,coupling agents, stabilizers, flame retardants, tougheners, epoxycompounds, mold release agents, nucleating agents, and colorants, canalso be present in the compositions of this invention, but are notnecessary. Such additives are generally present at 0.1 to about 45weight % based on the total weight of the polyester composition. Eachadditive may be present at such a level, and collectively the totalconcentration of additives may be higher. In one embodiment the blendcomprises from about 10 to about 200 pphr of reinforcing additivesand/or from about 30 to about 100 pphr of glass fibers.

The acid component of the polyester can be modified, preferably up to20%, more preferably only up to 10%, and still even more preferably onlyup to 5%. Dicarboxylic acids useful for such modification include, butare not limited to, aromatic dicarboxylic acids preferably having 8 to14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12carbon atoms, and cycloaliphatic dicarboxylic acids preferably having 8to 12 carbon atoms.

Particularly preferred examples of dicarboxylic acids other thanterephthalic acid to be used in forming the copolyester of the inventioninclude: isophthalic acid, naphthalene-2,6-dicarboxylic acid,1,4-cyclohexanedicarboxylic acid, 1,4-cyclohexanediacetic acid,diphenyl-4,4′-dicarboxylic acid, succinic acid, glutaric acid, adipicacid, azelaic acid, sebacic acid, and the like. Of these dicarboxylicacids to be included with terephthalic acid, isophthalic acid ispreferred. Copolyesters may be prepared from one or more of the abovedicarboxylic acids.

It should be understood that the dicarboxylic acid can arise from thecorresponding acid anhydrides, esters, and acid chlorides of theseacids.

The glycol component of the polyester may also be modified, with up to20 mole %, preferably up to 10 mole %, and more preferably up to 5 mole%, of one or more other aliphatic or alicyclic glycols. Such additionaldiols include cycloaliphatic diols preferably having 6 to 20 carbonatoms or aliphatic diols preferably having 2 to 20 carbon atoms.Examples of such diols are: ethylene glycol, diethylene glycol,triethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol,hexane-1,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol-(1,4),2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3),2,2-diethylpropane-diol-(1,3), hexanediol-(1,3),1,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)propane,2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,2,2-bis-(3-hydroxyethoxyphenyl)-propane, decalin diol and2,2-bis-(4-hydroxypropoxyphenyl)-propane.

Copolyesters may be prepared from two or more of the above diols.Ethylene glycol is a preferred glycol.

The copolyester resins useful in the blends of this invention are wellknown and are commercially available. Methods for their preparation aredescribed, for example, in U.S. Pat. Nos. 2,465,319 and 3,047,539.

The polyesters of the invention preferably have an inherent viscosity of0.1 to 1.2 dL/g, more preferably 0.1 to 0.9 dL/g, and even morepreferably, 0.4 to 0.8 dLg. The inherent viscosities (I.V.) of thecopolyesters are determined in 60/40 (wt./wt.) phenol/tetrachloroethaneat a concentration of 0.5 g/100 ml as determined at 25° C.

Copolyesters containing substantially only ethylene glycol,1,4-cyclohexanedimethanol and terephthalic acid or substantially onlyethylene glycol, 1,4-cyclohexanedimethanol, isophthalic and terephthalicacid are preferred in one embodiment.

Examples of reinforcing agents are glass fibers, carbon fibers, mica,clay, talc, wollastonite, and calcium carbonate. A particularlypreferred reinforcing agent is glass fiber. It is preferable that theglass fibers be present in the polyester composition at from 1 to 60%,preferably 10 to 40%, by weight based on the total weight of saidpolyester composition.

Glass fibers suitable for use in the polyester compositions of theinvention may be in the form of glass filaments, threads, fibers, orwhiskers, etc., and may vary in length from about ⅛ inch to about 2inches. Chopped glass strands having a length of about ⅛ inch to about ¼inch are preferred. Such glass fibers are well known in the art. Ofcourse, the size of these glass fibers may be greatly diminisheddepending on the blending means employed, even to lengths of 300 to 700microns or lower.

The polyester compositions of the invention may be reinforced with amixture of glass and other reinforcing agents as described above, suchas mica or talc, and/or with other additives.

The polyester compositions of the invention containing reinforcingagents may be molded at mold temperatures below 120° C. and aretherefore easily molded without the need for expensive mold heatingequipment. The preferred molding temperature of the glass filledpolyester compositions of the invention is in the range of 20 to 110° C.

The components of the blend of the invention may be blended and/or mixedby any suitable technology known in the art. Thus, in another embodimentthe invention provides a process for making a composition comprisingmelt mixing a blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is an integer of from 1 to 3;

ii. n is an integer of from 5 to 140;

iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbonsor less;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester comprises 100 mol parts acid residue, and 100 mol partsdiol residue;

ii. the polyester is semicrystallne; and

iii. the polyester has a melting point greater than 200° C.;

wherein the melt mixing is performed under sufficiently mild conditionsto avoid reaction between the polyester and the poly(alkylene ether).

A skilled worker will appreciate that the reaction conditions can beadjusted, based upon the composition employed, to avoid reaction betweenthe polyester and poly(alkylene ether), by for example reducing themixing time or temperature. Similarly, the composition can containadditives or the poly(alkylene ether)s can be endcapped, to reduce thelikelihood of reaction.

In still another embodiment the invention provides a process for makinga composition comprising melt mixing a blend comprising:

a. from about 1 to about 25 weight pphr of a poly(alkylene ether) havingthe formula (I) wherein:

i. m is 1;

ii. n is an integer of from 10 to 25;

iii. X is selected from hydrogen, methyl, ethyl, and propyl;

iv. A and B are independently selected from alkyl, acyl, or an arylresidue, of 1 to 200 carbons;

v. the number average molecular weight of A and B summed is greater thanabout 250; and

vi. the poly(alkylene ether) has a number average molecular weight offrom about 800 to about 6000; and

b. a polyester resin selected from modified and unmodified poly(ethyleneterephthalate), poly(propylene terephthalate), poly(butyleneterephthalate), poly(ethylene naphthalate), andpoly(1,4-cyclohexanedimethylene terephthalate), wherein:

i. the polyester is semicrystalline; and

ii. the polyester has a melting point greater than 240° C.

wherein the melt mixing is performed under sufficiently mild conditionsto avoid reaction between the polyester and the poly(alkylene ether).

In still another embodiment the invention provides a method of usingpolyester blends to reduce volatile emissions during drying, comprisingproviding the polyester blend recited above, and drying the polyesterblend at greater than 100° C. In a still further embodiment theinvention provides a method of using polyester blends to reduce volatileemissions during molding, comprising providing the polyester blendrecited above, and molding the polyester blend into a useful article. Ina preferred embodiment, one is able to process greater than 1,000lbs/day of polyester, without a plasticizer trap to capture volatileemissions, and with aftercoolers only, without fouling of theaftercoolers.

Molded objects and films may be prepared from the polyester compositionsof the invention including any preferred embodiment.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thecompounds claimed herein are made and evaluated, and are intended to bepurely exemplary of the invention and are not intended to limit thescope of what the inventors regard as their invention. Efforts have beenmade to ensure accuracy with respect to numbers (e.g., amounts,temperature, etc.) but some errors and deviations should be accountedfor. Unless indicated otherwise, parts are parts by weight, temperatureis in °C. or is at room temperature, and pressure is at or nearatmospheric.

The compositions reported in the following examples were prepared usingeither poly(1,4-cyclohexanedimethylene terephthalate) (PCT) orpoly(ethylene terephthalate) (PET) having inherent viscosities in therange of 0.5 to 1.00 dL/g as determined at 25° C. using 0.5 gram ofpolymer per 100 mL of a solvent composed of 60 wt % phenol and 40 wt %tetrachloroethane. The abbreviations “PCT” and “PET” in these examplesrefer to poly(1,4-cyclohexanedimethylene terephthalate) andpoly(ethylene terephthalate) respectively. Benzoflex 312 is thecommercial name for neopentylglycoldibenzoate and Benzoflex 552 ispentaerythritoltetrabenzoate. The abbreviations “DEH”, “DU”, “DO”, and“DS” refer to di-ethylhexanoate, di-laurate, di-oleate, and di-stearaterespectively.

The compositions were prepared by mixing the desired components on atwin screw extruder, extruded into a cold water bath and pelletized. Allcompositions are reported on a weight percent basis. Thermal analysis(DSC) and thermal gravimetric analysis (TGA) were performed on thecompounded pellets. Volatility during drying was determined by dryingthe samples in a desiccant drier at 120° C. for 4 to 16 hours. Theappearance of condensed volatiles in the after-cooler indicatedvolatility during drying.

The effectiveness of the plasticizer on increasing the crystallizationrate as well as lowering the optimum temperature for crystallization wasdetermined by evaluating the temperature of crystallization on heating(Tch) by DSC with a scan rate of 20° C. per minute after quenching fromthe melt. An effective plasticizer will lower Tch. Therefore, the lowerthe Tch value, the better the plasticizing effect.

Example 1 is a comparative PCT control utilizing no plasticizer. As canbe seen from example 1, PCT has a Tch of 133° C., a 0.5% weight losstemperature of 279° C. and has no volatility during drying. Example 2 isa comparative example utilizing 3.8% Benzoflex 312, a common plasticizerfor polyesters. As can be seen in example 2 this plasticizer lowers theTch of PCT to 114° C. The low 0.5% weight loss temperature indicatespotential volatility during compounding and molding and this plasticizeris volatile during drying.

Example 3 is also a comparative example, and utilizes a higher molecularweight organic ester, similar to Benzoflex 312, as the plasticizer. Astaught in the prior art, increasing the molecular weight of the organicester results in a less effective plasticizer for PCT as indicated byits significantly higher Tch for example 3 when compared to example 2.This organic ester is not volatile during drying or compounding, howeverit is still not desirable because it is not a good plasticizer. Example4 is a higher molecular weight organic ester from a poly(alkyleneether). This poly(alkylene ether) has been previously demonstrated to benon-volatile during compounding and it is an effective plasticizer,however it is volatile during drying.

Examples 5-12 are examples of this invention. These examples are madefrom higher molecular weight poly(alkylene ether)s with and withoutend-capping. These examples are effective plasticizers and are alsonon-volatile during drying and melt processing.

Examples 13-19 are all based on PET. Example 13 is a comparative exampleutilizing non-plasticized PET, and shows a high Tch of 156° C., and novolatility during drying. Examples 14 and 15 are comparative examplesutilizing effective plasticizers, but both plasticizers are volatileduring drying. Examples 16-19 are examples of this invention. Theseexamples use higher molecular weight poly(alkylene ether)s with andwithout end-capping. These examples are effective plasticizers and arealso non-volatile during drying and melt processing.

TABLE 1 Volatility of Poly(alkylene ether)/Polyester blends MolecularNumber .5% Volatile Poly(alkylene Weight of Repeat C atom/ Weight DuringPolyester ether) Wt % (g/mole) Units Ester Tg Tch Loss Drying  1 PCTNone 0 N/A N/A N/A 89 133 279 No  2 PCT Benzoflex 312 3.8  312 N/A 9.572 114 200 Yes  3 PCT Benzoflex 552 3.8  552 N/A 8.25 80 124 275 No  4PCT PEG-400-DEH 3.8  728 10 18 53 100 236 Yes  5 PCT PEG-600-DEH 3.8 948 15 23 55   90 242 No  6 PCT PEG-1000-DEH 3.8 1288 23 31 56  92 270No  7 PCT PEG-600-DL 3.8 1060 15 27 40  86 270 No  8 PCT PEG-600-DO 3.81225 15 33 54  90 272 No  9 PCT PEG-6000-DS 3.8 6569 136  154 86 133 275No 10 PCT PEG-400-DS 3.8 1009 10 28 68 101 293 No 11 PCT PEG-600-DO 3.81225 15 33 69 105 303 No 12 PCT PTMG-1000 5.0 1000 14 N/A 64 100 280 No13 PET None 0 N/A N/A N/A 80 156 No 14 PET Benzoflex 312 3.5 N/A N/A 9.5Yes 15 PET PEG-400-DEH 3.5  728 10 18 61 113 230 Yes 16 PET PEG-600-DL3.5 1060 15 27 63 114 269 No 17 PET PTMG-1000 3.5 1000 14 N/A No 18 PETPEG-1000-DEH 3.5 1288 23 31 65 119 No 19 PET PEG-1000-DS 3.5 1569 23 4166 119 No

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Otherembodiments of the invention will be apparent to those skilled in theart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. A method for reducing volatile emissions from polyester blends during drying comprising: a. providing a blend having: i. from about 1 to about 25 weight pphr of a poly(alkylene ether) having a number average molecular weight of from about 800 to about 6000 and represented by the formula:

wherein: m is an integer of from 1 to 3; n is an integer of from 5 to 140; X is selected from the group consisting of hydrogen, hydrocarbon, and amide having 10 carbons or less; A and B are independently selected from the group consisting of alkyl, acyl, and aryl residues having from 1 to 200 carbon atoms; and ii. a semi-crystalline polyester resin having melting point greater than 200° C. selected from the group consisting of poly(ethylene terephthalate), poly(propylene terephthalate), poly(butylene terephthalate), poly(ethylene naphthalate), and poly(1,4-cyclohexanedimethylene terephthalate); and b. drying said polyester blend at a temperature greater than 100° C.
 2. The method of claim 1 wherein m is
 1. 3. The method of claim 1 wherein n is from about 10 to about
 25. 4. The method of claim 1 wherein X is selected from the group consisting of hydrogen, methyl, ethyl, and propyl.
 5. The method of claim 1 wherein X is hydrogen.
 6. The method of claim 1 wherein the number average molecular weight of A and B summed is greater than about
 250. 7. The method of claim 1 wherein A and B are independently the residue of one or more fatty acids having from 10 to 20 carbon atoms.
 8. The method of claim 1 wherein said polyester is poly(ethylene terephthalate).
 9. The method of claim 1 wherein said polyester is poly(1,4-cyclohexanedimethylene terephthalate).
 10. The method of claim 1 wherein said blend further includes a phosphorous compound.
 11. The method of claim 1 wherein said blend further includes from about 10 to about 200 pphr of reinforcing additives.
 12. The method of claim 1 further comprising molding the polyester blend into a useful article.
 13. A method for reducing volatile emissions from polyester blends during drying comprising: a. providing a blend having: i. from about 1 to about 25 weight pphr of a poly(alkylene ether) having a number average molecular weight of from about 900 to about 1600 and represented by the formula:

wherein: m is 1; n is an integer of from 10 to 25; X is selected from the group consisting of hydrogen, methyl, ethyl, and propyl; A and B are independently selected from the group consisting of residues of one or more fatty acids having from 10 to 20 carbon atoms and wherein the number average molecular weight of A and B summed is greater than about 250; and ii. a semi-crystalline polyester resin having melting point greater than 200° C. selected from the group consisting of poly(ethylene terephthalate), and poly(1,4-cyclohexanedimethylene terephthalate); and b. drying said polyester blend at a temperature greater than 100° C.
 14. The method of claim 13 wherein X is hydrogen.
 15. The method of claim 13 further comprising molding the polyester blend into a useful article. 